Lubricating grease compositions from hydroxy phenyl fatty acids



Patented Oct. 19, 1954 LUBRICATING GREASE COMPOSITIONS FROM HYDROXY PHENYL FATTY ACIDS Jeffrey H. Bartlett, Westfield, Arnold J. Morway, Clark Township, Union County, and George E. Serniuk, Roselle, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 11, 1951, Serial No. 261,151

9 Claims.

This invention relates to lubricating grease compositions; particularly it relates to lubricating grease compositions having improved dropping points and a high degree of structural stability. More particularly the invention relates to lubricating grease compositions which are prepared by thickening the lubricating oil with a metallic soap of a phenolic fatty acid.

It has now been found and forms the object of this invention that outstanding lubricating grease compositions may be prepared by thickening a lubricating oil with a grease forming amount of the metallic soap of a phenolic fatty acid. These phenolic fatty acids contain a hydroxy group in the characteristic aryl structure and possess considerable advantages over the common grease forming fatty acids.

One method of preparation of the phenolic fatty acids contemplated'involves the alkylation of a phenolic material with a fatty acid or a long chain nitrile to form the acid. The hydroxylated aromatic material may be any of the well known phenolic materials such as phenol, cresols, naphthols, such as alpha naphthol, beta naphthol and alkyl or aryl naphthols, dior trihydric phenols, such as resorcinol, catechol, pyrogallol, and the like. It is important that the phenolic material be alkylated with a long chain acid, acid ester, or nitrile which contains from 10 to 30 carbon atoms, preferably, although not necessarily, in a straight chain. These acids, esters, or nitriles may be either saturated or unsaturated but are preferably unsaturated materials. The alkylation in this instance occurs at the position of the double bond. If a saturated material is chosen these compounds must first be chlorinated, the alkylation step then occurring through the condensation of the chlorinated product and phenolic body. Of the long chain unsaturated acids preferred there may be listed undecylenic, lauroleic, myristoleic, palmitoleic, oleic, gadoleic, erucic, ricinoleic, linoleic, linolenic, elaeostearic, licanic, arachidonic, clupanodonic, and the like. The naturally occurring glycerides of the fatty acids such as glyceryl oleate, etc., may also be used. These materials, after alkylation, are converted to the saturated compound. In the pre ferred embodiment oleic acid is used and becomes a phenolic stearic acid.

The alkylation procedure followed to form the fatty phenolic acids, to which the instant invention is directed, is straightforward and one with which the art is familiar. In general, it involves the reaction of a phenolic material with the desired unsaturate in the presence of an alkylation catalyst, the application of heat for a short period of time, and'purification of the resulting product. An example of the general procedure used to prepare the acids is set out in detail below:

PREPARATION OF HYDROXY-PHENYL STEARIC ACID A 3-liter flask was charged with 300 g. phenol (3.19 mols) and then BFs was introduced until there was an increase in weight of 46 g. To this was added 850 g. of commercial oleic acid during about 5 minutes. The reaction mixture was then cooled to room temperature. After standing at room temperature for 20 hours, the mixture was diluted with 500 cc. toluene. The resulting solution was washed four times with water containing a small amount of isopropyl alcohol to aid in breaking emulsions. The resulting product was steam distilled to a bottoms temperature of 310 C. leaving 692 g. of phenolic acid. This phenolic acid had a neutralization number of 84.6 and a saponification number of 166.

The preparation of the grease compositions of this invention is straightforward and involves problems with which the art of grease manufacture is familiar. The common alkali or alkaline earths may be used to saponify the phenolic acids to form the thickening agent in situ. That is to say, the acid may be admixed with a portion of the oil base, and the water solution of the metallic compound, usually in the form of a metallic hydroxide, is added to saponify the acid. It may also be desirable to preform the soap, followed by dispersion in the lubricating oil base. In this instance the neutralization reaction is brought to completion and the soap dried by the application of heat prior to incorporation with the lubricating oil base.

It may also be desired to incorporate with the soap of the phenolic fatty acid minor amounts of other conventional grease forming soaps. It

has been found advantageous, for example, to add minor amounts of lithium stearate to the lithium soap of hydroxy phenyl stearic acid. The

incorporation of the conventional soap forming materials may be accomplished by adding the desired fatty acid to the mixture and subsequently saponifying, or the thickening soap may be preformed and subsequently dispersed in the lubricating oil base. It has been found advantageous in some instances to incorporate with the phenolic fatty acid soap from about 1% to about 10% by weight of a conventional soap, preferably 2% to 8% by weight.

The art of lubricating grease manufatcure is familiar with the concept of complexing a conventional grease-forming soap with minor amounts of salts of low molecular weight acids such as acetic acid, furoic acid, and the like. The soaps of the phenolic fatty acids of this invention will also form desirable complexes with these low molecular weight acid salts, and it may be desirable, in some instances to form such a complex to impart additional high temperature properties to the finished formulation. Thus from 2% to of a metallic salt of an acid such as acetic, furoic, acrylic, erotonic, ethoxypropichic, and the like may be incorporated into the formulation, generally in approximately a 1:1 mol ratio to the high molecular weight soaps.

A brief description of the general method of preparing the greases of this invention is as follows:

The phenolic fatty acid is added to a portion of the lubricating oil in a grease kettle and raised to a temperature of between about 125 F. and 200 F. An aqueous solution of the desired metailic hydroxide is then added with stirring and the temperature is raised to the dehydration temperature. The balance of the lubricating oil base is then added and the temperature raised to above the transition temperature of the soap to about 350 F. to 500 F. The mass, when cooled, results in a grease cake which may be worked to an excellent-appearing smooth plastic product.

The lubricating oil base for the grease composition of this invention may be either a naturally occurring mineral base lubricating oil or a synthetic oil. As the mineral base lubricating oil there may be used a petroleum distillate from either the parafiinic or naphthenic base crudes refined by any of the conventional refinery techniques. The viscosity of the mineral base lubricating oil chosen will depend upon various factors, but a mineral oil having a viscosity between about 35 and 180 S. U. S. at 210 F. may be used.

Asa synthetic lubricating oil any of the commonly known synthetic lubricants are operable. The synthetic oils which may be used include such materials as the branched chain esters of dibasic acids, such as di-Z-ethyl hexyl sebacate; complex esters formed by admixing in various proportions a glycol or a polyglycol, a dibasic acid, and an alcohol; polymerized olefins, etc.

The saponifying agent used in the preparation of the grease compositions of .this invention may be any of the alkali or alkaline earths commonly used in grease making. These materials are usually added to the acid in the form of an aqueous solution of a metallic hydroxide.

' The use of the alkali metal hydroxide is preferable and among these sodium and lithium are especially preferred to form the phenolic fatty acid soap.

The amount of the grease forming soap used in the formulation of the reases of this. invention will vary, depending somewhat upon the consistency required in the final product. Generally speaking, from about 2% to about of the metallic soap of the phenolic fatty acid m'ay be dispersed in the desired lubricating oil. Lesser amounts than these are utilized for the formulation of softer greases and greater amounts for harder greases. It is particularly preferable to use from about 3% to about 10% in forming a general all-purpose grease.

The instant'invention is more explicitly defined by the following examples;

EXAMPLE I temperature until dehydration was complete.

There were then added an additional e8 parts of the oil and the mass heated to 400 F. and then cooled. There resulted an excellent-appearing grease composition which had the following properties:

ASTM penetration 77 F. mm./ 10:

Unworked penetration 210 Worked penetration (60 strokes) 230' Per cent free fatty acid as NaOH 0.3 Dropping point, F 440+ Structural stability to mechanical work- 3 ing Excellent Penetration after 106,000 strokes in the ASTM worker 250 EXAMPLE 1].

Formulation:

19.0% hydroxy phenyl stearic acid 2.3% lithium hydroxide. (monohydrate) 78.7% di-2-ethyl hexyl sebacate The hydroxy phenylstearic acid was neutralized with an aqueous solution of lithium hydroxide to a phenophthalein end point. The solution was stripped of water and the soap obtained was dispersed in the sebacateat 400 F. On cooling, it formed an excellent hard grease cake which on homogenization gave an excellent,

smooth, homogeneous product. The dropping point was 368 F.

EXAMPLE III Formulation:

50% grease of Example II 10% lithium stearate' 40% di-Z-ethyl hexyl sebacate The ingredients were mixed and heated to 400 F. and allowed tocool by quick chilling in thin layers. The formed a smooth cake. This was then homogenized to a smooth grease by working in the kettle.

EXAMPLES IV AND V The grease of Example 111 was converted to greases having very low soap content by adding additional ester, heating above the melting point, and then cooling. v

The data on these greases of Examples II-V are tabulated below:

Table I LITHIUM HYDROXY PHENYL STEARATE GREASES Formulation (Percent Weight) Ex. H

EX. III

Lithium Hydroxy Phenyl Stearate Lithium Stearate Di-Z-Ethyl Hexyl Sebacate Properties:

e (60 strokes).

Worked 220 220 Water Solubility (212 F.) Insoluble. Insoluble" Structural StabilityPenetration after 100,000 strokes in AS'IM worker 275 270 To summarize briefly, the instant invention relates to the formation of lubricating grease compositions which comprise a lubricating oil which has been thickened to a grease consistency with a minor amount of the alkali or alkaline earth metal soap of a phenolic fatty acid containing from to 30' carbon atoms in the non-aromatic portion thereof. A preferred embodiment contemplates the preparation of a grease by thickening either a mineral base oil or a synthetic lubricant, typified by di-Z-ethyl hexyl sebacate, with the alkali metal soap of hydroxy phenyl stearic acid. If desired, minor amounts of conventional greaseforming soaps may be incorporated in the formulation as well as minor amounts of salts of low molecular weight acids such as acetic acid, furoic acid, and the like. It is to be understood, of course, that other property-modifying additive materials, such as anti-oxidants, tackiness agents, and the like, may also be incorporated in the finished formulation.

What is claimed is:

1. A lubricating grease composition comprising a lubricating oil thickened to a grease consistency with an alkali metal soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the non-aromatic portion thereof.

2. A lubricating grease composition comprising a mineral lubricating oil thickened to a grease consistency with about 2% to 30% by weight of an alkali metal soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the non-aromatic portion thereof.

3. A lubricating grease composition comprising a lubricating oil thickened to a grease consistency with from 2% to 30% by Weight of an alkali metal soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the nonaromatic portion thereof.

4. A lubricating grease composition according to claim 3 wherein said alkali metal is sodium.

5. A lubricating grease composition according to claim 3 wherein said alkali metal is lithium.

6. A lubricating grease composition consisting essentially of di-2-ethyl hexyl sebacate thickened to a grease consistency with from about 2% to about 30% by weight of the lithium soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the non-aromatic portion thereof.

7. A lubricating grease composition comprising a lubricating oil thickened to a grease consistency with a mixture of from 2% to 30% of an alkali soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the non-aromatic portion thereof and from 2% to 5% by weight of an alkali metal salt of a low molecular weight acid complexed with said phenolic fatty acid.

8. A lubricating grease composition comprising a lubricating oil thickened to a grease consistency with a mixture of from 1% to 10% by Weight of an alkali metal soap of a high molecular weight substantially saturated fatty acid and from 2% to 30% by weight of an alkali metal soap of a hydroxy phenyl fatty acid containing about 18 carbon atoms in the non-aromatic portion thereof.

9. A lubricating grease composition consisting essentially of a mineral lubricating oil thickened to a. grease consistency with a mixture of from 3% to 10% by weight of lithium hydroxy phenyl stearic acid and from 2% to 5% by weight of the sodium salt of acetic acid which complexes with said hydroxy acid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,081,075 Vobach May 18, 1937 2,095,538 Vobach Oct. 12, 1937 2,180,697 Vobach Nov. 21, 1939 2,180,698 Vobach Nov. 21, 1939 2,180,699 Vobach Nov. 21, 1939 2,223,127 Prutton Nov. 26, 1940 2,239,953 Fairlie Apr. 29', 1941 OTHER. REFERENCES Klemgard, Lubricating Greases (1937). Gilfoil, Notes on Lubricating Greases Made from the Soaps of Phenyl-Stearic Acid (1930). 

1. A LUBRICATING GREASE COMPOSITION COMPRISING A LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH AN ALKALI METAL SOAP OF A HYDROXY PHENYL FATTY ACID CONTAINING ABOUT 18 CARBON ATOMS IN THE NON-AROMATIC PORTION THEREOF. 